Alternative Engine Buyer’s Guide

A look at the non-traditional engine alternatives and PSRUs for homebuilt aircraft.


In a category called Experimental aircraft youd expect there to be, well, a lot of experimentation. We have the freedom to do our own thing, and it seems a shame to waste it. Such an attitude is no more vividly displayed than with alternative engines for homebuilts. In the last of our yearly Buyer’s Guides, well look at the offerings for homebuilders in this category, which we see as including both tried-and-true auto-engine conversions (and engines both closely and loosely based on auto engines) such as the Volkswagen, as well as some truly alternative, small-volume designs.


As in years past, we have contacted each company for an update on its products, asked for revised pricing, availability and number of engines delivered-notice the terminology, thats delivered, not sold.

Changes for the 2010 guide? Well, we failed to make contact with a few companies, and some said that certain engines were no longer available. For example, despite repeated attempts we could not connect with VairForce, a second company offering Corvair conversions. (Its our policy that companies that cant be bothered to return phone calls or answer emails probably cant support their product.) Among those we did talk to: Powersport is no longer offering the RE-360 rotary; Verner has discontinued the Scarlett radials; Eggenfellner has dropped the E6T and E6-Ti Subarus to concentrate on the standard E6 engine; and Vesta is no longer trying to develop the Chevy 6.6-liter DuraMax diesel.

What are you in for should you select an alternative engine? Depends. Indeed, both your skill level and your ability to work out solutions on the fly will help determine the quality of your installation, as will the development work done by the engine or firewall-forward package (FWF) provider. Its safe to say that not all alternative engines or engine packages are created equal, and just because a supplier says its plug-and-play, that doesn’t mean it really will be.

Because of the wide range of engine choices, its hard to create solid groupings across the board-groupings that might help you with an apples/apples comparison-but there are a few. The venerable Volkswagen flat-four engine remains a favorite for builders on a tight budget. Its ascendance to popularity came because there are just so many of them in the world; with the right modifications and technical approach, the VW engine can be a reliable, honest little airplane powerplant. Also, because of its configuration, the flat-four Subaru engine remains popular, as does the Corvair opposed-six.

Geared Drives, PSRU clutch view.

From there, the category diversifies, with engines designed from various other off-the-shelf components, including a range of automotive engines. Chevys landmark small-block V-8 is always a popular choice for builders who need high horsepower and desire a V-oriented engine. Whats more, the lure of the rotary engine, most often based on the Mazda-refined Wankel format, continues to be irresistible for builders. A number of companies are producing whole engines as well as providing kits for engines. Along those lines, we also provide a listing of companies that will sell their propeller-speed reduction units (PSRUs) for installation on your own engine choice. (Please note that we’ve listed the Rotax gearboxes for convenience, though technically they’re not supposed to be used on any engine besides a Rotax. The fact that they are available separately from the engines suggests their inclusion here.)

As with all things in the Experimental-aircraft market, the quality of the components and the customer orientation of the companies can vary greatly. Its our strenuous recommendation that you look closely at two data fields we provide here. One is the number of engines delivered. The other is the highest-time engine field. We ask every company to provide these data points, and many decline. When those numbers are small or unavailable, we urge you to step up your research efforts. Insist on contact with actual owners of the engine in question and learn what they like or dislike about the powerplant or firewall-forward package. Do not count on the veracity of online resources ranging from engine-specific bulletin boards to owner testimonials-particularly in the more public forums, the quality of information can be tainted by a small group of malcontents or by a groups fear of retribution by the manufacturer. You might be getting an overly cheerful view of the engine in question, or an overly gloomy one. Reader feedback also suggests that some of the listed availability times might be optimistic. One of the leading complaints appears that vendors over promise on delivery times. If you are the true tinkering type, this wont be a bother or a surprise, but if you’re new to this end of the homebuilt market, you need to be prepared to be flexible.

We do our best to look for new engine designs. If we’ve missed something, please let us know at [email protected].

Rotary Engines

Mazdas version of the Wankel rotary engine is by far the most common, though there are a few offerings that share little to nothing with the Japanese powerplant. The idea of the Wankel is compelling: Each rotor has three combustion chambers and, overall, the engine works more like a two-stroke in that the power pulses come more frequently than in a four-stroke piston engine. But most interesting is that the Wankel eschews any reciprocating motion, and as such has an almost turbine-like smoothness. The Wankels traditional problems, including the reputation for high fuel consumption, have largely been addressed, and there’s nothing like the small size of the powerplant to give builders installation flexibility. All of the current rotary offerings require a PSRU.


Base PriceBase PowerInductionCoolingDry Weight (lb)No. of RotorsPropHighest Time Engine (hrs.)Availa-bilityNotes
A650, 100 hp$10,500 100 @ 6000 rpmCarb 100  10012 weeks2 delivered.
Global Rotary Power Inc.,
GRP-NRR-CA, 40 hp 40 @ 6000 rpmCarbLiquid381  2 weeksGlobal Rotary has declined to submit prices or offer the number of engines delivered.
GRP-WAG-Fi 1, 40 hp 40 @ 6000 rpmInj.Liquid651  2 weeks 
GRP-WST-MF-1 65 hp 65 @ 6000 rpmInj.Liquid1431  6-8 weeks 
GRP-WAG-Fi-2, 80 hp 80 @ 6000 rpmInj.Liquid1152  10 weeks 
GRP-WST-MF-2, 130 hp 130 @ 6000 rpmInj.Liquid1762 1500  
GRP-DAFi-13B, 180 hp 180 @ 6000 rpmInj.Liquid 2  3 weeks 
GRP-DAFi-13BT, 200 hp 200 @ 6000 rpmInj.Liquid 2  3 weeksTurbo-
GRP-WST-MF-3, 220 hp 220 @ 6000 rpmInj.Liquid2203 15004 weeks 
Mistral Engines,
G-200, 200 hp 200 @ 2250 (prop rpm)Inj.Liquid2912Hartzell or MT, 3 blade  FAA and EASA Type certification expected beginning 2011. TBO estimated at 3000 hours.
G-230TS, turbocharged, 230 hp 230 @ 2250 (prop rpm)Inj.Liquid3282Hartzell or MT, 3 blade  In develop-
ment. FAA and EASA Type certification expected 2011.
G-300, 300 hp 300 2 2250 (prop rpm)Inj.Liquid3902Hartzell or MT, 3 blade  FAA and EASA Type certification expected end of 2010.
G-360TS, turbocharged, 360 hp 360 @ 2250 (prop rpm)Inj.Liquid4202Hartzell or MT, 3 blade  In develop-
ment. FAA and EASA Type certification expected 2011.
Powersport Aviation,
RE-215 Rotary, 215 hp$24,500 215 @ 2620 (prop rpm)Inj.Liquid2572Fixed or MT 3 blade, electric constant speed20012 weeks9 delivered.
RE-250 Rotary, 250 hp$28,500 250 @ 2700 (prop rpm)Inj.Liquid2572Fixed or MT 3 blade, electric constant speed 12 weeksNew porting configuration and injector develop-
ment; no engines sold yet with this porting configu-

Maxwell Propulsion.

Subaru Engines

Carmaker Subaru has an excellent reputation for powerplant durability, but its perhaps the opposed-cylinder orientation that makes the Subie a viable choice for homebuilts. All current Subaru products are opposed-piston designs of four or six cylinders. All are liquid cooled and electronically fuel injected. Depending on the particular engine chosen, you could get double overhead camshafts or single cams per bank, but all of the current offerings have four valves per cylinder, long a staple of the modern-auto world. Because of their high-revving nature, all Subaru packages currently offered require PSRUs, which has an impact on all-up weight and prop choices. In this category, Eggenfellner has dropped the E6T and the E6-Ti turbocharged models for a single E6, normally aspirated, 200-horsepower engine, and added a conversion for the Honda Fit engine (seen in the Other Engines category). Maxwell, as we said in the February issue, is working hard on a turbocharged version of the single-cam EJ25 engine.

Base PriceBase PowerInduct
CoolingDry Wt. (lb)No. of Cyl.Prop.No. Deli-
Highest Time Engine (hrs.)Avail-
Eggenfellner Aircraft, Inc.,
Subaru E6, 200 hp$17,995 200 @ 2700 (prop)Inj.Liquid3706IVO Magnum14011004 monthsE6T and E6-Ti models disc-
ontinued. Complete FWF package.
Maxwell Propulsion Systems, Inc.,
MX1, 165 hp$20,115 165 @ 5200 rpmInj.Liquid3384MPS CAP 22014 8 weeksTuned to use 87 octane mogas. Two-year limited warranty on FWF engine packages including PSRU and propeller, starting at $26,830.
MX2 Stroker, 195 hp$27,000 195 @ 5200 rpmInj.Liquid3384MPS CAP 2204 8 weeksTuned to use 93 octane mogas or 100LL. Two-year limited warranty. FWF engine packages with MPS PSRU upgrade starting at $33,715.
MX3 Turbo, 240 hp$29,100 240 @ 5200 rpmInj.Liquid3384MPS CAP 220  14 weeksIn develop-
ment. Tuned to use 92 octane mogas or 100LL, two-year limited warranty, FWF engine packages with MPS PSRU upgrade starting at $35,850.
RAM Performance Ltd.,
Subaru RAM 2.3L SC, 300 hp $21,995 300 @ 2700 (prop rpm)Inj.Liquid2354Prince P-Tip4503 months 
Subaru RAM 2.3L, 200 hp$15,995 200 @ 2450 (prop rpm)Inj.Liquid2204Prince P-Tip252008 weeks 
Subaru RAM SC, 140 hp$18,995 140 @ 2500 (prop rpm)Inj.Liquid1884Prince P-Tip503008 weeksSuper-
Subaru RAM, 115 hp$13,995 115 @ 2500 (prop rpm)Inj.Liquid1764Prince P-Tip25018008 weeksIncludes redrive and motor mounts.
Stratus 2000,
EA81, 105 hp$8,995 105 @ 3200 rpmCarbLiquid2004Warp Drive 3-blade, wide chord, ground adjustable18512002-3 months


Vesta V8.

Other Engines

Then there’s our catch-all category, one meant to encompass those engines that aren’t easily grouped with others. Here you’ll find everything from a small-block Chevy V-8 to purpose-built aero engines. The Corvair is in here, too, now that were down to just one supplier in the field, the indefatigable William Wynne. In making your decisions, look carefully at the number of engines delivered and all-up weight. Be sure to consider a bit of fudge factor for liquid-cooled engines-some companies list the engine weight with accessories and cooling-system components, while others do not.

Base PriceBase PwrInduc-
Wt. (lb)
Prop.No. Delive-
est Time Engine (hrs.)
Eggenfellner Aircraft, Inc.,
Honda Fit Conversion, 110 hp$12,995 110 @ 2700 (prop)Inj.LiquidI-4IVO Medium,
FlyCorvair Corvair, 100-130 hp$7,995 100 @ 3200 rpmCarbAir218-
O-6Wood or comp.655002 mo.Displace-
ments available from 164-169 cubic inch.
Geared Drives,
LS Series Aluminum Chevrolet Corvette for RV-10, Bearhawk, Glasair III, other O-540 applica-
tions, 320 hp
$29,900 320 @ 4300 rpmInj.Liquid488V-8Cust. choice of hydraulic, electric or fixed pitch54-5 mo.Complete FWF package.
LSJ Aluminum Chevrolet, 150-245 hp$29,900 150 @ 4800 rpmInj.Liquid470I-4Cust. choice of hydraulic, electric or fixed pitch24-5 mo.Aluminum four-cylinder Chevy engine. Complete FWF package.
Hexatron Engineering Co. Inc.,
Hexadyne P60 Champ, 60 hp$8,800 60 @ 5750 rpmInj.Air94I-3Warp drive, Powerfin, Kiev, fixed or adjust.4818001 wk.Four aircraft flying.
Powerplant Developments-USA, Inc.,
Gemini 100, 100 hp$18,000 100 @ 2500 rpm155I-3Est April 2011Still in develop-
ment. Three-cylinder, six-piston compres-
sion-ignition design developed for LSA market.
Raven ReDrives,
1000 UL, UL-T, ULRS-T Turbo, 80 hp$7,850 80 @ 5700 rpmInj.Liquid152I-3Ivoprop, Powerfin, GSC, wood155002-3 wks.Price includes complete engine package.
1000 ULDD, 38 hp$4,975 38 @ 3400 rpmCarbLiquid93I-32 blade wood1103-4 wks.Price includes complete engine package.
1000 ULRS, ULRS-T, 60 hp$5,996 60 @ 5700 rpmInj.Liquid140I-3Ivoprop, Powerfin, GSC, wood246502-3 wks.Price includes complete engine package.
1000 ULX, UL, UL-T, 60 hp$5,749 60 @ 5700 rpmInj.Liquid130-
I-3Ivoprop, Powerfin, GSC, wood23610004-6 wks.Price includes complete engine package.
1300 SV/1300 SVS Turbo, 115 hp$11,495 115 @ 5700 rpmInj.Liquid195-
I-4Ivoprop, Powerfin, GSC, wood8504-6 wks.
1300 SV/1300 SVS, 90 hp$8,595 90 @ 5700 rpmInj.Liquid175-
I-4Ivoprop, Powerfin, GSC, wood382504-6 wks.Price includes complete engine package.
Trace Engines,
OE-600, 600 hp$200,000 600 @ 4400 rpmInj.Liquid600V-8McCauley21300Immed.FAA Type and Production certified.
Valley Engineering,
Big Twin 992 4-stroke, 40 hp$4,995 40 @ 3600 rpmCarbAir110V-2Culver two-blade wood prop included.453502 wks.Price includes electric start, PSRU, prop and exhaust.
VE 85, 85 hp$7,500 85 @ 3800 rpmCarbAir180H-4Culver two-blade wood prop included.41001 mo.Price includes Diehl case, electric start, PSRU and prop.
VE 100, 100 hp$9,995 100 @ 3800 rpmCarbAir185H-4Culver two-blade wood prop included.407501 mo.Price includes Diehl case, electric start, PSRU and prop.
Verner Light Aircraft Engines,
Verner JCV-360, 38 hp$8,275 38 @ 7500 rpmCarbLiquid57O-252 inch28-12 wks.
VM133MK, 84 hp$9,900 84 @ 5500 rpmCarbAir134O-268-72 inch570025008-12 wks.Based on BMW motorcycle cylinder assemblies. Fuel injection to be available 1Q10.
Vesta, Inc.,
Chevy 572 Big Block, 550 hp$26,900 550 @ 4500 rpmInj.Liquid780V-8Vesta HT 84-1024 mo.
Ecotec 2.2L-2.4L, 160-200 hp$11,900 160 @ 5000 rpmInj.Liquid300I-4Vesta GT2, GT3 68-78, LT2 80-83.4 mo.Up to 200 hp @ 5400 rpm available.
Honda 3.5L-3.7L V-6, 240-310 hp$13,900 240 @ 5000 rpmInj.Liquid340V-6Vesta GT2, GT3, GT4 68-78, LT4 80-83, VP3-82, VP4 70-824 mo.Up to 310 hp @ 4800 rpm available. FADEC controlled.
LS3-376 V-8, 380-430 hp$15,000 380 @ 4500 rpmInj.Liquid460V-8Vesta HT3, HT4 76-84, RT3, RT4 89-92, HT3 84-102, VP3 82, VP4 70-82.4 mo.Up to 430 hp @ 4800 rpm available. FADEC controlled.
* Configuration key: I-3, inline three cylinder; I-4, inline four cylinder; V-8, V-arrayed eight cylinder; V-6, V-arrayed six cylinder; O-4, opposed four cylinder; O-6, opposed six cylinder.


Volkswagen Engines

The opposed-four-cylinder Volkswagen engines share some major characteristics, though the development of the breed as aero engines has led to a number of modifications and novel solutions. Youll find the Vee-Dub engine as both air- and liquid-cooled, though air cooling is by far the most common choice. A variety of displacements are available, and you’ll find them as both direct-drive and with various PSRUs. The trade-offs are well-known. A geared engine can turn faster and make more power for a given displacement, but the cost is weight and complexity. Direct-drive versions are simpler and, usually, lighter, but they have certain prop limitations. While all VW-based packages are four-stroke designs, there are many, many variations of internal components, accessories and horsepower ranges.

Manufacturer/ModelBase PriceBase PowerInductionCoolingDry Weight (lb)PropellerNo. Delive-redHighest Time Engine (hrs.)Availability
AeroVee 2.1, 80 hp$6,495 80 @ 3400 rpmTBIAir161Fixed pitch wood or comp.46310004-6 weeks
Great Plains Aircraft Supply Co.,
1600cc VW Direct Drive, 50 hp$3,400 50 @ 3400 rpmCarbAir145-164Wood231800Immediate
1835cc VW Direct Drive, 60 hp$3,900 60 @ 3400 rpmCarbAir145-162Wood1051800Immediate
1915cc VW Reduction Drive, 80 hp$4,900 80 @ 4200 rpmCarbAir178Wood21175Immediate
2180cc VW Direct Drive, 76 hp$4,500 76 @ 3400 rpmCarbLiquid165Wood1800+2500Immediate
2180cc VW Flywheel Drive, 80 hp$6,000 80 @ 3400 rpmCarbAir185Wood37 Immediate
2180cc VW Redrive, 103 hp$5,500 103 @ 4200 rpmCarbAir188Wood or comp.37175Immediate
Hummel Engines,
Hummel 2- & 4-Cylinder VW, 28-85 hp$3,700 28 @ 3000 rpmCarbAir80-16754×20 to 62×32400+12004-6 weeks
Revmaster Aviation,
R2100-D, 75 hp$6,800 75 @ 3200 rpmCarbAir175Standard fixed, oil controls337020001-2 months
R2200-D, 100 hp$6,800 100 @ 3250 rpmCarbAir Standard fixed, oil controls   
R3000-D, 110 hp* 110 @ 3200 rpmCarbAir205Fixed pitch8  
* Note: In development; prototype engines only delivered.



Finally, prop-speed reduction units. Many FWF providers will sell a PSRU separately for an engine installation of your own design, while other companies specialize in just PSRUs. As always, contact the company directly to understand if the engine you propose to install will mate with any given PSRU.

ManufacturerModelPrice TypeRatioMax Engine PowerWeight (lb)PropellerNotes
Alturair, alturdyne.comA650 PR$6,495 Gear, Planetary3:0110035  
American Rotary Engines, $6,500 Gear, Straight2.29:1, 2.39:130055No hydraulic pitch governor; electric only6 delivered, 2-3 weeks shipping time.
Belted Air Power, $5,600 Belt1.43:12604874 inch, 35 lb.200+ delivered, 2 weeks shipping time.
Compact Radial Engines, compactradial
RZ Gearbox$1,580 Helical GearFive availa-
13028 800 delivered, 2 weeks shipping time if not in stock.
Eggenfellner Aircraft, Inc., eggenfellner
 $4,495 Gear (Unspecified)2.01:120038Wood or composite propeller500+ delivered, immediate shipping time.
Geared Drives, $9,500 Spur Gear1.616:1, 1.72:140063Customers choice of fixed-pitch, hydraulic or electricNew CNC case costs extra. 20 delivered, 120-180 days shipping time.
Global Rotary Power Inc., $1,370 Belt2:1, 3:18014  
Great Plains Aircraft Supply Co., greatplainsas.comValley Series 3$1,595 Belt1.6:1, 2.0:1, 2.47:110517Wood96 delivered, immediate shipping time.
 Valley Series 3$1,595 Belt1.6:1, 2.0:1, 2.47:112017Wood or composite101 delivered, immediate shipping time.
Maxwell Propulsion Systems, Inc.,
Autoflite$3,800 Helical Gear1.9:1, 2.2:1, 2.4:1, 2.9:130038-58Reverse rotation, tractor or pusher, recommend CAP-220Dealer for Autoflite PSRU, 8 weeks shipping time.
  $8,950 Helical Gear2.13:130072Reverse rotation, tractor or pusher, recommend CAP-22013 delivered, 8 weeks shipping time.
Powersport Aviation, powersport
 $6,495 Straight Gear2.29:1, 2.39:1, 3:130057Standard prop rotation12 delivered, 4-12 weeks shipping time; three-rotor engines must use special torsional pulley.
RAM Performance Ltd., $3,600 Helical Gear1.9:1, 2.1:1, 2.47:1, 2.9:11603672 inch50 delivered, 2 months shipping time.
  $3,895 Helical Gear1.9:1, 2.1:1, 2.47:1, 2.9:12003872 inch2 delivered, 2 months shipping time.
  $4,100 Helical Gear1.9:1, 2.1:1, 2.47:1, 2.9:13004280 inch4 delivered, 2 months shipping time.
Raven ReDrives,
1000ULDD for Geo three cylinder$1,295   3895Two-blade, woodConversion kit for direct-drive 38 hp, 95 lb. 1 delivered, 3-4 weeks shipping time.
 1000ULRS-T for Geo three cylinder$2,695 Belt2.26:18019Ivo, Powerfin, GSC, wood34 delivered, 3-4 weeks shipping time.
 1000ULX, UL, UL-T for Geo three cylinder$2,295 Belt2.26:18017Ivo, Powerfin, GSC, wood236 delivered, 3-4 weeks shipping time.
 1300SV, 1300 SVS for Geo three cylinder$3,595 Belt2.26:112017-22Ivo, Powerfin, GSC, wood38 delivered, 3-4 weeks shipping time.
Real World Solutions, rotaryaviation.comRD-1B$3,315 Planetary Gear2.176:130044Fixed-pitch or electric constant speed. No length or weight limitations. Drive approved for recreational type aerobatics.69 delivered, 6-8 weeks shipping time.
 RD-1C$3,315 Planetary Gear2.85:130044Fixed-pitch or electric constant speed. No length or weight limitations. Drive approved for recreational type aerobatics.102 delivered, 6-8 weeks shipping time.
Recreational Power Engineering, recpower.comCogbelt Re-Drive$1,550 Belt2.6:17015Prop up to 72 inch40 delivered, 3-4 weeks shipping time.
 G-40$1,665 Helical Gear2.03:1, 2.25:1, 2.46:1, 2.79:1. 2.96:1, 3.33:1, 3.79:112024Prop up to 76 inch550 delivered, 3-4 weeks shipping time.
 G-50$1,465 Helical Gear2.03:1, 2.25:1, 2.46:1, 2.96:1, 3.33:1, 3.79:110019 1750 delivered, immediate shipping time.
B Gearbox Helical Gear2.0:1, 2.24:1, 2.58:16410Limitation of 3000 kg/cm25000+ delivered, immediate shipping time.
 C Gearbox Helical Gear2.62:1, 3:1, 3.47:1, 4:17518Limitation of 6000 kg/cm25500+ delivered, immediate shipping time.
 E Gearbox with integrated E/S  Helical Gear2.62:1, 3:1, 3.47:1, 4:17525Limitation of 6000 kg/cm25500+ delivered, immediate shipping time.
Stratus 2000,
EA81 Subaru$3,000 Belt2.2:112545Any SAE #1 bolt pattern195 PSRUs delivered, 1 week shipping time.
Valley Engineering, culverprops.comV-Twin$1,295 Belt1.61:1 – 2.92:1506Recommend Culver wood two-blade25 delivered, 3 weeks shipping time.
 VW Type One$1,595 Belt1.61:1 – 2.92:11208Recommend Culver wood two-blade250 delivered, 3 weeks shipping time.
Vesta Inc., $3,500 Chain1:1 – 3.1:160045-100Manufactured for Vesta propellersFive chain widths available (1.0, 1.5, 2.0, 3.0 and 4.0 inch). Supports hydraulic governor.


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